I have just begin to understand collections in Java. I read about the differences between LinkedList and ArrayList but have several doubts on it. I have mentioned them below
1) Why retrieving in ArrayList is faster then LinkedList?. Since both have the get method how does performance differ?.
2) How does re-sizing happens internally in ArrayList when a item is added or removed?. How slow this is compared to the pointer re-shuffling in LinkedList when a item is added or removed?.
My remove(item E) method is working fine if I remove an item that is in the list. However, it has an error when I try to remove an item which is not on the list!
Linked List Class
import java.util.NoSuchElementException;
public class LinkedList<E> { private Node<E> head; // head node of the list private int size = 0; // number of elements that have been added to the list // Returns the element at a specific list index. // Big-O: O(n) (due to the nodeAt call, which must traverse the list) public E get(int index)
I'm doing LinkedList at the moment and I'm having a bit of trouble with my assignment. The part I'm struggling with is remove an employee from a training course (as specified by their employee number),
what I'm confused about is iterating through the linked list to find the employee we're looking for. What I would do in this situation if I was using an array list is
for(Employee emp : myList) { if(emp.getEmployeeNumber().equals(searchedNumber)) { remove from training course.. break; } }
"Can only iterate over an array or an instance of java.lang.Iterable" is what it is telling me, and I can't figure out why/how its done differently for linked lists.
Okay, I'm having a problem with my LinkedList. When I run the driver program it's telling me that I have no "add" method and I don't know what's going on.
Driver Program:
public class TestLinkedList { public static void main(String[] args) { MyLinkedList<String> L = new MyLinkedList<String>(); L.add("Browns"); L.add("Ravens"); L.add("Steelers");
I can't figured out why it's keep giving me error when I tried to add i to the linkedlist. I tried changing it to other numbers but keep giving me nullExceptionPointer.
public static void subset(double[] weight, double[] value, int start) { double sumWeights = 0; for(int i = start; i<weight.length; i++){ if(sumWeights+weight[i]>L){ continue;
I have a Queue class (containing a LinkedList plus a few other variables and stats for my project), which works fine with the standard LinkedList, but I'm trying to add my own code for MyLinkedList.
However, I keep getting a NullPointerException at my remove method.
public class MyLinkedList<T> { Node head; public MyLinkedList() { head = null; } public class Node { T contents; Node nextNode;
I am getting "Type safety: Unchecked cast from Object to LinkedList<EventData>" in eclipse for a piece of code stated below
public LinkedList<EventData> loadFromFile(File file) { queue=new LinkedList<EventData>(); //Some piece of code return (LinkedList<EventData>)queue.clone(); //--->getting warning here }
I know that because clone() method is returning Object, hence compiler doesn't have type information that's why showing warning. I don't want to suppress this warning instead i want to fix it.
I am new to java i dont understand the difference between the abstract and inheritance i mean we use the abstract class with extends with other class name ,even we do that same in the inheritance pls tell me main difference between abstract and inheritance...
I have been tasked with creating an invoice (school assignment). Part of the calculations is creating an interest depending on the amount of days between the current date entered, and invoice date entered (The program prompts the user to enter both the current and invoice dates by asking for the day, month and year).
We are also supposed to set the contructor to a default date of 1/1/1900.. but I don't know how or where to code that.
How to calculate the difference between the CurrentDate and Invoice. I have displayed the dates to the user as follows.
I read that InputStream is used for byte based reading it reads 1 byte at a time.And InputStreamReader is used for charcter based reading so it reads one charcter at a time so no need to convert this first to int then read it.Here is reading using InputStream.
input=new FileInputStream("D:/input.txt"); int c; while((c=input.read())!=-1) { System.out.print((char)c); }
and here is reading using InputStreamReader
input=new FileInputStream("D:/input.txt"); reader=new InputStreamReader(input,"UTF-8"); int c;
so what is difference between InputStream and InputStreamReader in both case i have to use a Int and then read it and at the end if I want to print that data I have to cast that with "(char)c".So what is advantage of using InputStreamReader?
I know that oracle has released a statement saying that JavaFX will eventually replace Swing. What is the advantage of JavaFX? The new format, using "stage" instead of JFrame, seemed weird. Why is this change necessary? What benefit do we reap from JavaFX that Swing does not have?
Im working on my homework and it mentioned element for one exercise and an index in another, what is the difference, If Any, Between An Element And An Index?
If I am making an application using Java SE8 and I use new concepts of JavaSE8 like "Lambda Expressions" and "Default Methods".
After completing my application I give it to client who are using Java Platform less than 8 like Jdk1.7._; then will this application will work fine as it is working on JavaSE8.
a JavaSE8 application works well on Java SE7 platform.